1. Field of the Invention:
The present invention relates to a PDA (personal digital assistance) device.
2. Description of the Related Art:
Japanese Laid-Open Patent Publication No. 59-23664 discloses a conventional automatic dialing unit as illustrated in FIG. 5.
The automatic dialing unit illustrated in FIG. 5 includes: a modular jack 2 for connecting the automatic dialing unit to a telephone line 1; a diode rectifier 3 for rectifying a telephone line voltage of the telephone line 1 to the same polarity regardless of the polarity of the telephone line voltage; a constant-voltage power supply circuit 5 for supplying a voltage required for the automatic dialing unit; a RAM 7 for storing a telephone number to be dialed; a backup battery 8 for saving data stored in the RAM 7; a control circuit 6 for receiving from the RAM 7 the telephone number data to be dialed and outputting a dialing signal; a dial switch circuit 4 for outputting a dial pulse signal by opening/closing the telephone line 1 according to the dialing signal received from the control circuit 6; and an associated telephone 9 for closing the telephone line 1 so as to activate the constant-voltage power supply circuit 5.
Referring to FIG. 5, when the associated telephone 9 is placed in the off-hook state, the telephone line voltage of the telephone line 1 activates the constant-voltage power supply circuit 5 via the diode rectifier 3. The constant-voltage power supply circuit 5 supplies to the control circuit 6 a power for operating the control circuit 6.
The control circuit 6 performs automatic dialing by controlling the dial switch circuit 4 according to the telephone number registered in the RAM 7 which saves its data by means of the backup battery 8.
When the associated telephone 9 is placed in the on-hook state, the power supply from the telephone line 1 to the diode rectifier 3 stops, thereby turning off the control circuit 6. In the "off-hook state" as used herein, the handset is taken off the hook, where a voltage of about 48 V is applied to the device. In the "on-hook state" as used herein, the handset is put on the hook, where a voltage of about 4 V is applied to the device.
In recent years, as small note-book PCs and PDA devices have become wide-spread while the PC network/internet environment has expanded with public telephones with a modular jack having become common, the PC communication environment including the internet (inter alia the outdoor communication environment) has been improved. Accordingly, the number of users who use such a communication environment has increased.
The automatic dialing unit illustrated in FIG. 5 performs automatic dialing by a simple and easy operation of placing the handset of the associated telephone in the off-hook state. However, the automatic dialing unit illustrated in FIG. 5 requires an associated telephone for performing automatic dialing, while the function thereof is limited to automatic dialing.